As a related-art surround component generation device, there has been known a stereo reproduction device having two signals of L and R signals as its signal source. The stereo reproduction device emits an L signal from a first speaker and an R signal from a second speaker in proportion to a degree of mismatch between the L and R signals, emits an (L+R) signal from a third speaker or an imaginary sound source speaker arranged between the first speaker and the second speaker in proportion to a degree of match between the L and R signals, and, to acquire the degree of mismatch and the degree of match, calculates a difference or correlation coefficient between the L and R signals or both thereof (see, for example, Patent Literature 1).
Further, as another related-art surround component generation device, there has been known a device including: correlation coefficient arithmetic means for inputting left and right signals L and R of an acoustic component signal to calculate a correlation coefficient K based on the left and right signals L and R; delay means for outputting left and right signals L′ and R′, which have been delayed by a period of time required for arithmetic processing of the correlation coefficient arithmetic means; left and right component signal arithmetic calculation means for performing arithmetic processing of L′(1−K) and R′(1−K) based on the delayed left and right signals L′ and R′ and the correlation coefficient K to calculate left and right component signals L″=L′−KL′ and R″=R′−KR′; center component signal arithmetic means for performing arithmetic processing of K(0.5L′+0.5R′) based on the delayed left and right signals L′ and R′ and the correlation coefficient K to calculate a center component signal C″=K(0.5L′+0.5R′); left and right reproduction output means, which are arranged on the front side of a listener, for reproducing and outputting the left and right component signals L″ and R″, respectively; and center reproduction output means, which is arranged between the left and right speakers, for reproducing and outputting the center component signal C″ (see, for example, Patent Literature 2).
Further, as still another related-art surround component generation device, there has been known an audio device for generating surround signals for a plurality of channels based on two-channel audio signals as input signals. The audio device includes an adaptive correlation eliminating device including: a correlation eliminating filter for dividing the input signal of one of the channels by a multi-stage delay processing device, superimposing a predetermined coefficient on each of the divided multi-stage outputs by a coefficient processing device to generate multi-stage output components, and adding the multi-stage output components, thereby extracting signal components having a high correlation with the input signal of another of the channels from components of the input signal of the one of the channels; and a coefficient updating processing device for constantly varying characteristics of the correlation eliminating filter based on an error signal obtained with use of the output signal of the correlation eliminating filter and the input signal of the another of the channels, the input signal of the one of the channels, and a step size parameter for controlling an update rate for a filter coefficient. The audio device calculates a difference between the output of the correlation eliminating filter and the input signal of the another of the channels to output the difference as the surround signal (see, for example, Patent Literature 3).